April 26, 2009

Swine Flu

"The World Health Organization rushed to convene an emergency meeting Saturday to develop a response to the "pandemic potential" of a new swine flu virus that has sparked a deadly outbreak in Mexico and spread to disparate parts of the United States.

Health officials reported that at least eight students at a private high school in New York City had "probable" swine flu. They also confirmed three new cases -- two in Kansas and one in California -- bringing the total number of confirmed U.S. cases to 11. The president of Mexico, where the outbreak has killed as many as 81 people, issued an order granting his government broad powers to isolate patients and question travelers. (...)

The virus, for which there is no vaccine for humans, has nearly brought Mexico City to a halt. Normally congested downtown streets in this city of 20 million were almost empty Saturday, and of the few people who ventured outside, many said they did so only out of necessity. Soldiers posted at subway stations handed out face masks to passersby from the back of armored vehicles. Some pedestrians covered their mouths and noses with scarves and rags.

"We can't escape the air," said Antonio Gonzáles, 56, who wore a surgical mask outside a public hospital. "If it was something in the food, we'd have a chance."

The Mexican government reported more than 1,300 suspected cases of the virus, which mixes animal and human strains of flu. Bars and nightclubs, schools, gallery openings and sporting events were cancelled until further notice. Authorities advised people to wash their hands regularly and avoid the customary greeting of kissing on the cheek. The government issued a decree giving the Health Ministry power to enter people's homes, close public events, isolate patients, and inspect travelers and their baggage.

The Associated Press reported that 24 new cases of the flu emerged Saturday in Mexico."

Thus far, the Mexican version seems to be much more virulent than the US version, despite the fact that "partial comparisons of the genetic sequences of the Mexican and American cases shows them to be essentially the same". There could be any number of explanations for this: "some difference in the information (looking at severely ill versus routine surveillance of outpatients), some difference in the virus (while the viruses are said to be "genetically identical" this is true only in the parts that have so far been compared) or some co-factor (e.g., co-infection with another pathogen)."

However, it seems likely that there has been human-to-human transmission, which is worrisome. Moreover, the casualties in Mexico seem to have been disproportionately healthy young adults. On NPR today, Laurie Garrett gave two possible explanations for this: it might be that children and the elderly got the regular flu vaccine, and that it confers some protection to this new strain of influenza, which would be good; or it might be the dreaded cytokine storm: basically, a lethal overreaction by the immune system. This is thought to be the reason why young adults were disproportionately represented among the casualties of the pandemic of 1918: since they have stronger immune systems, the overreaction was more likely to be fatal.

If we're lucky, this will continue to be relatively mild in this country, and the steps Mexico is taking will do the trick. Just in case, though, now might be a good time to download this flu manual (pdf; h/t DemFromCT at dKos.) Unnecessary preparation beats being caught unprepared by a flu pandemic.

Comments

Thanks for posting this. It might be the start of a pandemic, but it is more likely just a bit of a preview for the inevitable flu pandemic that lies in our future. In the latter case, the good that comes from it (not to diminish at all the tragedy of those who have died from this outbreak) will be better preparation for that eventuality.

I doubt many people sick with the flu are going to be walking across our border. Dying in the attempt, maybe, but it's a fairly strenuous way to enter illegally. Nor would even a reasonable legal level of traffic between the US and Mexico effectively block a flue pandemic. So it would be pretty silly to link the issue to illegal immigration.

Stock enough food and other supplies so that you don't have to go to the grocery for a month or two, and rubber gloves and face masks for when you absolutely have to go out, and you ought to be able to wait out the worst of it, if it does get bad. These are sensible precautions that are relatively cheap.

Masks only work if you wear them almost all the time. [...] Intent-to-treat analysis showed no significant difference in the relative risk of ILI in the mask use groups compared with the control group; however, Either wear it night and day, in or out of the house, more or less 100% of the time, or don't bother.

[...] Intent-to-treat analysis showed no significant difference in the relative risk of ILI in the mask use groups compared with the control group; however, <50% of those in the mask use groups reported wearing masks most of the time. Adherence to mask use was associated with a significantly reduced risk of ILI-associated infection. We concluded that household use of masks is associated with low adherence and is ineffective in controlling seasonal ILI. If adherence were greater, mask use might reduce transmission during a severe influenza pandemic.

[...]

We present the results of a prospective clinical trial of face mask use conducted in response to an urgent need to clarify the clinical benefit of using masks. The key findings are that <50% of participants were adherent with mask use and that the intention-to-treat analysis showed no difference between arms. Although our study suggests that community use of face masks is unlikely to be an effective control policy for seasonal respiratory diseases, adherent mask users had a significant reduction in the risk for clinical infection. Another recent study that examined the use of surgical masks and handwashing for the prevention of influenza transmission also found no significant difference between the intervention arms (12).

Our study found that only 21% of household contacts in the face mask arm reported wearing the mask often or always during the follow-up period. Adherence with treatments and preventive measures is well known to vary depending on perception of risk (27) and would be expected to increase during an influenza pandemic. During the height of the SARS epidemic of April and May 2003 in Hong Kong, adherence to infection control measures was high; 76% of the population wore a face mask, 65% washed their hands after relevant contact, and 78% covered their mouths when sneezing or coughing (28). In addition, adherence may vary depending on cultural context; Asian cultures are more accepting of mask use (29). Therefore, although we found that distributing masks during seasonal winter influenza outbreaks is an ineffective control measure characterized by low adherence, results indicate the potential efficacy of masks in contexts where a larger adherence may be expected, such as during a severe influenza pandemic or other emerging infection.

[...]

We emphasize that this level of risk reduction is dependent on the context, namely, adults in the household caring for a sick child after exposure to a single index case. We urge caution in extrapolating our results to school, workplace, or community contexts, or where multiple, repeated exposures may occur, such as in healthcare settings. The exact mechanism of potential clinical effectiveness of face mask use may be the prevention of inhalation of respiratory pathogens but may also be a reduction in hand-to-face contact.

Either wear it night and day, in or out of the house, more or less 100% of the time, or don't bother.

The 1918 flu pandemic (commonly referred to as the Spanish flu) was an influenza pandemic that spread to nearly every part of the world. It was caused by an unusually virulent and deadly Influenza A virus strain of subtype H1N1. Historical and epidemiologic data are inadequate to identify the geographic origin of the virus.[1] Most of its victims were healthy young adults, in contrast to most influenza outbreaks which predominantly affect juvenile, elderly, or otherwise weakened patients. The pandemic lasted from March 1918 to June 1920,[2] spreading even to the Arctic and remote Pacific islands. It is estimated that anywhere from 20 to 100 million people were killed worldwide,[3] or the approximate equivalent of one third of the population of Europe,[4][5][6] more than double the number killed in World War I.[7] This extraordinary toll resulted from the extremely high illness rate of up to 50% and the extreme severity of the symptoms, suspected to be caused by cytokine storms. The pandemic is estimated to have infected up to one billion people: half the world's population at the time.[8]

[...]

The global mortality rate from the 1918/1919 pandemic is not known, but is estimated at 2.5 to 5% of the human population, with 20% or more of the world population suffering from the disease to some extent. Influenza may have killed as many as 25 million in its first 25 weeks (in contrast, AIDS killed 25 million in its first 25 years)[citation needed]. Older estimates say it killed 40–50 million people[3] while current estimates say 50 million to 100 million people worldwide were killed.[13] This pandemic has been described as "the greatest medical holocaust in history" and may have killed more people than the Black Death.

"Either wear it night and day, in or out of the house, more or less 100% of the time, or don't bother."

That's not what it said. It was a study of houses with somebody already infected in them. Of course you'd have to wear one all the time in such an environment. This doesn't imply you'd have to wear one in your sleep to avoid catching the flu if you go out of the house.

Brett: I doubt many people sick with the flu are going to be walking across our border. Dying in the attempt, maybe, but it's a fairly strenuous way to enter illegally. Nor would even a reasonable legal level of traffic between the US and Mexico effectively block a flue pandemic. So it would be pretty silly to link the issue to illegal immigration.

Not seeing much evidence in these numbers that the virus is less virulent in the US. In Mexico the mortality rate is not even 1 in 15 of the reported cases while only 11 cases have so far been reported in the US. I would also think that it would be quite likely that many non-serious cases in Mexico would have gone unreported.

Grist has a piece up today which suggests that the source of the infection is a Smithfield Corp. hog-raising and slaughter facility in a place called Perote, outside Mexico City.

Theirs was the first mention I'm aware of which links a specific locale to the origin of the disease, or links any corpoRat deeds to the outbreak.

Not that I am a fan of factory farming by a long shot, but if I remember my Jared Diamond correctly, humans and domesticated critters have been passing germs back and forth since the beginnings of domestication.

At least so far, it appears that the known cases in the U.S. and Canada have more to do with tourism than illegal immigration. And if (still a big if) it turns out to be a deadly pandemic, the wide geographic distribution of those cases suggest the cat is already out of the bag. That's not going to stop racist paranoia, of course, which needs little if any excuses.

As a way of avoiding the cytokine storm caused by a top-notch immune system, I intend to launch a regimen of late nights and strenuous drinking. Where my health is concerned, no sacrifice is too great.

Hartmut, there won't be much fun in the outside anyway, and you'll stick at home as much as possible. Better to buy a few surgical masks as long as they are available. Not comfortable, of course, but you will need them when dealing in the public.

I was just saying that a necessity to wear the mask constantly will lead to most people not doing it for the inconvenience.
Btw, do they work without extra impregnation with biozides?
Btw, I guess masks are already out and hand disinfectants too (and unfortunately I do not work at the hospital anymore since my civil service ended).

Yes, the nutjobs are on it: The whole swine flu scare is just a diversion to push the nomination of Kathleen Sebelius through (so say Concerned Women for America nad Glenn Beck).
Actually, I did not suspect/expect that specific rubbish (but I hear also that it is already used for immigration bashing too)

Hartmut, there are nutjobs on all sides (though as usual the right-wing nuts seem to be in more powerful and prominent positions). I heard a radio caller (on a sane, non-Limbaughvian show) ranting about how Donald Rumsfeld owned the North American distribution rights for Tamiflu and this scare was all about profits for him and other Republicans.

Oh, I forgot that Rummy was in the Obama administration ;-)
From the left I'd expect slightly different claims (of the bioweapon research gone wrong tpye). Let's put it this way, the drug companies will of course try to make a buck on this but I doubt that they are behind the scare (and only real whackos* would believe that they spread the virus for that purpose).
Wake me when flying pigs are named as the main vector (hey, it's a hybrid of avian/porcine/human flu).
My apology, if this comes over as snarky but there are already a lot of people dead, so I have not much tolerance for conspirationists of either political persuasion. But the left ones can usually be ignored (in the US. Europe is different there)

*this type of conspiracy theory can be found on both ends of the spectrum and I'd be surprised, if noone came up with it.

While we are at absurdities: the Israeli Ministry of Health has announced that the term swine flu should not be used because pigs are unclean from the Jewish point of view. Instead it should be designated Mexican flu. The WHO concurs because the precise origin of the virus is still not fully clear.

Unbelievable how many people comment material unrelated to the core of the matter.I guess, its the way things are.However the posting is amazing and informative.I am about to travel to South America, including Mexico, around June and I am wondering how things will be,but I will travel even if Al Kaida,Rumsfeld & the his folks are behind it.Should you really look for credible info,please check the World Health Organisation.Another good source I found was from activagers.

It would appear that factory farming may be the most likely cause of the current outbreak (just as it was for the avian flu several years ago). For more see Priming the Pump of a Swine Flu Epidemic at Nature Network.

I think that this is the goverments way of taking us over totally and make a one world goverment... I dont know about you all but I dont want a RFID chip in my hand. I dont want to be made to have deadly vaccines.. WAKE UP PEOPLE .. look up NEW WORLD ORDER online.. fema death camps...

This site is actually quite funny - but doesn't ANYONE find it suspicious that it is swine/swine/human/bird flu combined - and does ANYONE really know how many people in mexico have it or even have died from it? It is my experience that the mexican government is neither accurate or forthright in statistics....

Aside from the political problems with "undocumented workers" or "immigrants".....realspeak = illegals, should we really continue to allow people across the border in hoardes, even if it is to seek better treatment? The borders are flooded with people trying to escape. Do you want it in your school, grocery store, fast food joint? The schools in Texas are closing at an alarming rate!

"Aside from the political problems with 'undocumented workers' or 'immigrants'.....realspeak = illegals, should we really continue to allow people across the border in hoardes, even if it is to seek better treatment?"

As someone upthread noted, tourists (i.e. American citizens) -- not illegals -- is what seems to have brought the swine flu into the United States.

Does that mean we should disallow American citizens the right to foreign travel? You never know what one may pick up abroad.

Melle, for good and for ill, globalization is here to stay.

Also, the fact that this particular strain has characteristics of swine/human/bird flu combined is what has scientists particularly grappling for answers.